Motor and sail powered displacement boats generate a bow wave, followed by a trough and stem wave, due to hull form and friction. For a displacement boat, the bow wave increases in amplitude with boat speed until propulsion power is insufficient to climb the wave (i.e., the hull speed limit). The bow wave, when generated, initially moves forward at the hull speed, but eventually loses speed and moves at an angle away from the hull. When the bow wave does so, it has sufficient energy to threaten other nearby boats and cause damage to foundations at the water/land interface in narrow waterways. In addition, engines mounted on the stem of the boat generate strong propeller wave action and noise pollution, which are especially objectionable to residences and/or commercial buildings located near the water/land interface. These problems are accentuated when boats operating at low speeds are required to make sharp-angle turns in narrow waterways, such as in the canals of Venice, Italy. Because a rudder is less effective under such conditions, an articulating outboard motor (or propeller), which accentuates the generation of waves and noise pollution, may be required.
The problems associated with the operation of smaller displacement boats powered by stem-mounted internal combustion engines include:
1. Conventional power boats are designed as either: (a) displacement boats, efficient at low speeds but subject to hull speed limits; or (b) planing boats, inefficient at low speed but with sufficient power and planing surface to transcend the hull speed limits; PA1 2. As mentioned above, bow waves generated by a boat move forward initially at the boat speed, but thereafter at decreasing speed due to friction, leading to potentially destructive bow waves moving laterally away from the boat; PA1 3. A significant portion of propulsion energy is lost when converted into wave energy, leading to inefficiency; PA1 4. Bow and stem waves plus stem-mounted propeller wave action generated by boats operating at high speed can cause serious damage to other boats and to foundations at the water/land interface in narrow waterways and small lakes; and PA1 5. Wave, noise, and air pollution generated by conventional displacement boats powered by internal combustion engines are accentuated with an articulating outboard motor or propeller.